A leading ballerina at Milan's La Scala who criticised what she described as a plague of anorexia among dancers has been summarily sacked by the company as it launches its 2012 season.

Mariafrancesca Garritano, 33, has been fired for "damaging the image" of La Scala after claiming that one in five ballerinas suffered from anorexia.

In an interview with the Observer last December, Garritano lifted the lid on the regime at La Scala's dance school, where she said she had been pressured into losing weight after being accepted at 16. She says she still suffers intestinal pains and frequent bone fractures which she believes are linked to dieting, and claims that colleagues – who like her went on to join La Scala's ballet company – were unable to have children.

"I talk to people coming through the system and it seems nothing has changed," she said last year.

Carlo Maria Cella, La Scala spokesman, appeared to accept that students had been placed under severe pressure in the past, but denied Garritano's claim that the academy was still turning out anorexic ballerinas.

"Saying that La Scala is similar to what Garritano says she experienced 15 years ago is false," he said. "Educational methods used then are not used today and the school now has a course on nutrition. As for not having children, nine of Garritano's fellow dancers have become pregnant in the past year-and-a-half."

But a former colleague of Garritano's told the Observer that all was not well with today's dancers. "One in five of the ballerinas of that generation from that school had eating disorders, and continue to experience serious consequences," said Michele Villanova, 47, a senior dancer at La Scala between 1986 and 2010. "I saw it in the mood swings, when people would go into deep depression after gaining weight. It is absurd the La Scala fired her before carrying out an in-depth investigation."

Anorexia and bulimia were recently portrayed in the Oscar-winning film Black Swan, in which Natalie Portman forces herself to throw up to keep her weight down.

Garritano said she knew she risked losing her job over her revelations. Villanova said: "Dancers are afraid to speak out, and what happened to Garritano shows why."

Recalling his time at the academy in 1980, Villanova said: "There was an atmosphere that tended to make students prioritise their physical form, just at the time their bodies were changing. You cannot be obsessive about losing weight when you are 14."

After spending a short spell studying in Milan, Villanova was sent to continue his training with the Bolshoi in Moscow, where, he says, he found a less draconian approach to weight. "They had a canteen with high-calorie foods and looked after students," he recalls. "If I had carried on studying in Milan, I don't think I would have made it through."

Not all ballerinas back Garritano. Colleagues at La Scala reacted with hostility to her claims and Eleonora Abbagnato, 33, who works with the Paris Opera, condemned her as a publicity seeker. "Nothing of what she says is true," she told Italy's La Repubblica. "I have worked with many theatres up and down Italy and have not seen anorexics, or instructors and directors who made ballerinas obsess about excessive diets. Your physique is important, even fundamental, but how can you not eat when you are training for seven or eight hours a day?

"If they called her names like Mozzarella, it means she had problems with muscle tone. Maybe she should have tried another profession."

The dieting accusations come as another example of the life of ballet stars comes to the boil in London. Sergei Polunin, the Ukrainian dancer appointed as the Royal Ballet's youngest ever principal dancer aged 19, stepped down in dramatic fashion last month after reportedly saying he planned to give up dancing because the pressure was too great.

Revered as the new Rudolf Nureyev, Polunin became co-owner of a tattoo parlour while working at the Royal Ballet and had taken to sending out cryptic tweets in the runup to his shock resignation. Enrolled at ballet school by his poor parents, he has said he craved a normal life but was pushed hard by his family. "There was no chance of me failing," he has said.

Villanova, who now teaches dance, says he insists on talking to parents about why their children want to enter the ballet: "The parents are often just concerned their children get a place to study. What they don't understand is that the first years of studying are hugely important from an emotional point of view."